iOS 8.3 (build 12F70) is an official Apple over-the-air update for the iPhone 6, released on 2015-04-08T17:56:16Z. The update package is 534.51 MB. This is a delta (partial) update that requires 8.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: f64834974ce605fe68e9a02136015ee1757d2d8c.zip.